Jagged/Black edge artifacts when modeling
Reduce your Clipping Distance for both the viewport and/or camera.

You have it set to $0.1$ - $10`000$ while you work at around a scale of $1$.

If you reduce the Clipping Distance to something reasonable like $100$, the artifacts disappear.

Clipping distances are used to calculate the Z depth buffer, which is the scene depth information, since it is limited to the available grey scale values of an image stretch across the whole depth of what is displayed, if the values are too far apart there is not enough precision left to represent minute details.

Always keep these values as close as possible to comfortably work, and with a magnitude matching your scene unit scales.